solution5a.cpp

#include <string>
#include <iostream>
#include<utility>
#include<algorithm>
#include<fstream>
#include<thread>
#include<functional>
#include<array>
#include<vector>


std::string removeCharFromString(std::string input, char target){
    std::string result;
    for (auto &c: input) {
        if ((c != target) && (c+32 != target) && (c-32 && target)){
            result.push_back(c);
        }
    }
    return result;
}

std::string decomposeWithStack(std::string input) {
    std::vector<char> returnVal;
    returnVal.push_back(0); // otherwise the .back call segfaults;
    for (auto &c: input) {
        if (c+32 == returnVal.back() || c-32 == returnVal.back()) {
            returnVal.pop_back();
        } else {
            returnVal.push_back(c);
        }
    }
    return std::string(returnVal.begin()+1, returnVal.end()); // to compensate for that first push_back
}

// Pretty much useless at this point, overtaken by the function above
std::string decomposeString(std::string input) {
    if (input.length() < 2){ return input; }
    
    for (auto i = 0; i != input.length()-1; i++) {
        if (input[i]+32==input[i+1] || input[i]-32==input[i+1]) {
            return std::move(input.erase(i, 2));
        }
    }
    return input;
}

std::string totalDecomposition(std::string input) {
    std::string result;
    while (true) {
        //result = decomposeString(input);
        result = decomposeWithStack(input);
        if (result == input) { // decompose didnt change anything
            return result;
        }
        input = result;
    }
}

void totalOperation(std::string input, const char target, std::array<std::string, 26> &stringplace) {
    auto trunc = removeCharFromString(input, target);
    stringplace[(int)target-97] = totalDecomposition(trunc);
}

int main() {
    std::ifstream t{"input.txt"};
    std::string ex;
    std::getline(t, ex);
    auto result = totalDecomposition(ex);
    std::cout << "Actually removed" << (ex.size() - result.size()) << std::endl;

    int removed;
    std::string shortest_string(1<<20, 'a');
    char most_impactful_letter;
    std::thread threads[26];
    std::array<std::string, 26> truncatedStrings;
    for (char i = 0; i != 26; i++) {
        threads[i] = std::thread{totalOperation, result, (char)i+97, std::ref(truncatedStrings)};
    }
    for (char i = 0; i != 26; i++) {
        threads[i].join();
    }
    char letter = 97;
    char myletter = -1;
    for (auto &s: truncatedStrings) {
        if (s.size() < shortest_string.size()) {
            std::cout << s << " " << letter << std::endl;
            shortest_string = s;
            myletter = letter;
        }
        letter++;
    }

    std::cout << "Shortest string is " << "a" <<" with length " << shortest_string.size() << std::endl;
    std::cout << "The letter was " << myletter << std::endl; 
    return 0;
}